JPH05249828A - Developing unit for image forming device - Google Patents

Abstract

PURPOSE:To surely stir recycled toner supplied in a developing unit and to always stabilize the concentration of the toner in the developing unit. CONSTITUTION:In the developing unit 6, an auxiliary stirring member 23, a partition 24, the main stirring member 22 and a developing sleeve 21 are disposed in paralell in order from above, with spaces left between them. Toner supplied in the developing unit 6 is stirred together with carrier around the stirring members 23 and 22 along a loop-like developer-passage S shown by arrows. A toner concentration sensor 29 is provided near the right end of the auxiliary stirring member 23 on the developer passage S. A recycle toner supply position R is set on the developer passage S and in the position where developer has just been supplied to the right end of the developer sleeve 21 or the position which is in the vicinity of that on the downstream side. A fresh toner image supply position N is provided between the recycle toner supply position R and the toner concentration sensor 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for supplying recycled toner and new toner supplied to a developing device of an image forming apparatus such as a copying machine or an image scanner.

[0002]

2. Description of the Related Art Generally, an electrophotographic image forming apparatus such as a copying machine or an image scanner comprises a platen on which a document is placed, a document irradiation lamp which reciprocates below the platen, a reflection mirror, and a fixed projection lens and a reflection mirror. A photosensitive drum that is endlessly rotated by a scanning optical system and a band electrode that are charged with a predetermined potential, and toner is applied to the electrostatic latent image formed on the surface of the photosensitive drum by the scanning optical system. A developing device for developing the toner image, a transfer electrode for transferring a toner image onto a recording paper surface which is a transfer material conveyed below the surface of the photosensitive drum, a separation electrode and a removing electrode, and the recording paper surface. The fixing device fixes the toner image transferred onto the surface of the photosensitive member, and the cleaning device removes the toner and paper dust remaining on the surface of the photosensitive member after the transfer. In a recent popular type copying machine, for example, a process cartridge in which a cartridge in which a belt electrode, a photosensitive drum, a cleaning device and the like are unitized and a developer cartridge which can be separated and connected to the cartridge are combined into one is used as an image forming apparatus. It's quite compact because it's removable.

The toner collected by the cleaning device is supplied to the developing device by the recycling device and is reused.

When a required toner image is successively recorded on the surface of the recording paper which is intermittently conveyed along a predetermined conveying path and the image forming apparatus makes repeated copies, the toner in the developing device is gradually consumed. If necessary, toner is replenished from the toner replenishing device to keep the toner density in the developing device constant and to always develop a good toner image.

[0005]

Generally, the toner concentration in the developing device is detected by a toner concentration sensor provided near the position where new toner is supplied.

The amount of recycled toner returned to the inside of the developing device is not always constant but constantly changes depending on the copy conditions of the image forming apparatus. Therefore, depending on the position where the toner is supplied to the developing device, agitation is not sufficient, and the toner is also a toner Since the detection of the density becomes uncertain, the toner density in the developing unit changes, which adversely affects the toner image formed on the photosensitive drum. Regarding such means for supplying recycled toner, Japanese Patent Laid-Open Publication No. 54-121133 and Japanese Utility Model Laid-Open No. 61-89869 disclose technical means, but both technical means are agitators for sufficiently agitating recycled toner. The means for the time is unclear, and uncharged toner may be supplied to the developing sleeve in some cases.

The present invention solves such a problem and provides a developing device of an image forming apparatus capable of always stabilizing the toner concentration in the developing device even when the toner amount changes and uncertain recycled toner is supplied. Is the task objective.

[0008]

[Means for Solving the Problems]
b is achieved by any means.

(A) In a developing device of an image forming apparatus equipped with a toner recycling device for collecting the toner remaining on the surface of the image carrier after transfer and supplying it to the developing device, the developing device is agitated with at least the developer. A plurality of agitating members, a partition plate, and a developing sleeve are provided, and the developer that has been agitated through the periphery of the agitating members that are parallel to each other on both sides of the partition plate is applied to the developing sleeve. Immediately after or after finishing the application of the developer to the developing sleeve on the developer flow path in which a loop-shaped developer flow path that circulates around each stirring member again is formed after shifting to the stirring of new developer A developing device of an image forming apparatus, characterized in that a supply position of recycled toner is provided on the downstream side in the vicinity.

(B) In (a), the supply position of the new toner is a recycled toner supply position provided on the developer flow path, and a toner concentration detection means arranged downstream of the recycled toner supply position. A developing device for an image forming apparatus, which is provided between the developing device and the developing device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a top view showing a stirring state of a developer and a supply position of recycled toner in FIG. 1, an explanatory view showing a supply position of new toner in FIG. 2 and a developing device in FIG. A side sectional view showing the configuration and a side sectional view showing the configuration of the image forming apparatus in FIG. 4 will be described. However, the present invention is not limited to this embodiment.

As shown in FIG. 4, an electrophotographic image forming apparatus 18 is provided.
A platen glass P for placing a document M is provided on the upper surface of the main body 1, and a scanning optical system 2 is provided below the platen glass P in the main body 1. The scanning optical system 2 includes a reciprocating document irradiation lamp 2a, a first mirror 2b, second and third mirrors 2c forming a V shape, and a fixed lens 2.
d and the fourth mirror 2e. A photoconductor drum 3 is rotatably provided in the center of the main body 1 in the direction of the arrow, and a belt electrode 4 for uniformly charging the photoconductor 3a along the rotation direction is provided around the photoconductor drum 3, and a toner replenishing device. 5, a developing device 6 in which the toner is replenished with toner and a developing sleeve 6a is incorporated, a transfer electrode 7, a separation electrode 8, a charge eliminating electrode 9, and a cleaning device 10 are sequentially arranged. Paper cassette 11,1
Two types of recording papers having different sizes are stored in 1'and set in the main body 1. 12 is a paper cassette 11
Is a first paper feed roller that feeds the recording paper stored in to a standby position before the second supply roller 13, and is a roller 12a that is rotated via a belt to prevent double feeding of the recording paper.
12a and a stop roller (also referred to as a separating roller) 12b. 13 is an appropriate timing so that the recording paper fed by the first paper feed roller 12 is temporarily stopped at the standby position, and then the leading edge of the visible image on the photoconductor 3a and the leading edge of the recording paper are aligned at the transfer position. The second paper feed roller 14 that feeds paper again toward the transfer position at 14 is a guide plate for guiding the recording paper fed by the first paper feed roller 12 to the position of the second paper feed roller 13, It is opened and closed by operating a lever (not shown) so that the jammed paper can be taken out by inserting a hand. Reference numeral 15 is a conveying device that conveys the recording paper after transfer to a fixing position, and the fixing device 16 is a heating roller.
16a and pressure roller 16b. Reference numeral 17 denotes a paper discharge roller that discharges the recording paper after fixing to the outside of the main body.

As shown in the figure, a first cartridge 20 containing the belt electrode 4, the photosensitive drum 3, and the cleaning device 10, a second cartridge in which the developing device 6 and the toner replenishing device 5 are unitized. Process cartridge which is divided into two parts such as 30 and can be combined and separated from each other.
40 is detachably attached to the image forming apparatus 18.

When the copy button is operated in the above apparatus, the original M on the platen glass P is exposed and scanned by the scanning optical system 2, and an electrostatic latent image of the original M is formed on the photoconductor 3a of the photoconductor drum 3. It This electrostatic latent image is made into a visible image by the developing device 6, and this visible image is the paper feeding cassette of the main body 1.
Transfer electrode 7 is applied to recording paper fed from either 11 or 11 '.
Transcribed by After the transfer, the recording paper is separated from the photoconductor 3a by the separation electrode 8 and is fixed by the conveying device 15 to the fixing device 16a.
The sheet is conveyed to the sheet, is fixed there, and is ejected by the sheet ejection roller 17. In this way, desired toner images are successively recorded on the recording paper surface.

After the transfer, the residual toner adhering to the peripheral surface of the photosensitive drum 3 is scraped off by the blade of the cleaning device 10 and once collected in the cleaning device 10, it is then recycled by a recycling device (not shown). It is supplied into the developing device 6 and used again.

When the image forming apparatus 18 repeats copying, the toner in the developing device 6 is gradually consumed. Therefore, toner is replenished from the toner replenishing device 5 as necessary to keep the toner density of the developing device 6 constant. A good toner image is always developed.

The positions for supplying the recycled toner and the new toner of the present invention were set as follows.

As shown in FIG. 3, the developing device 6 includes a main stirring member.
22. Agitator for developer by 22 and auxiliary agitating member 23 and partition plate 24
28, the developing sleeve 21, and H for controlling the spike of toner
The cut plate 25, a housing 26 to which these members are attached, and an upper cover 27 integrally mounted to the housing 26.

A toner replenishing device 5 into which a toner cartridge 19 is loaded is integrally attached above the developing device 6 and is unitized to form a second cartridge 30. The auxiliary stirring member 23 of the developer stirring device 28 is a screw-shaped member having a right-handed spiral angle that rotates in the clockwise direction indicated by the arrow, and the main stirring member 22 that rotates in the same direction indicated by the arrow is the auxiliary stirring member. It is a screw-shaped member with a left-handed helix angle opposite to 23. And the auxiliary stirring member
23 is equipped with a screw having a smaller diameter and a finer pitch than the main stirring member 22 and is set with emphasis on stirring property.
Has a screw with a coarser pitch and a diameter larger than that of the auxiliary stirring member 23, and the feeding force is set more importantly than the stirring property.

Although not shown, the main stirring member 22 has a screw shape in which an elliptical plate is continuously provided in the longitudinal direction, or a water wheel-shaped scraping portion is also provided in the longitudinal direction. It doesn't matter which one you have. However, the screw shape of the auxiliary stirring member 23 differs depending on the screw shape of the main stirring member 22, and is appropriately set according to mutual stirring properties, transportability, and the like.

Then, as shown in FIG. 1, a main stirring member 22 and an auxiliary stirring member which are arranged in parallel with each other with a partition plate 24 interposed therebetween.
Of the developer stirring device 28, such as the auxiliary stirring member 23
The toner supplied near the right end of the auxiliary stirring member 23
The toner and carrier are mixed and agitated in the course of being conveyed toward the right end portion of the auxiliary stirring member 23 by the thrust force of 3 to be a homogeneous developer which is frictionally charged.

The developer reaching the left end portion of the auxiliary stirring member 23 makes a U-turn at the left end surface of the partition plate 24 as a boundary and makes a main stirring member.
It is conveyed to 22 and the conveyance is started while being further stirred by the thrust of the main stirring member 22 in the right direction indicated by the arrow.

The developer sequentially conveyed to the right by the main agitating member 22 is sequentially arranged from the left end of the peripheral surface of the developing sleeve 21 arranged in parallel with the main agitating member 22 at a predetermined interval to the right end. It is given toward the department. Then, after a predetermined amount of developer is applied to the developing sleeve 21, the excess developer is further turned around the right end of the partition plate 24, conveyed to the auxiliary stirring member 23, and reaches the toner supply position again. It is agitated by circulating it through the above-mentioned route.

In this way, a developer flow path S in the form of a loop is formed which agitates the developer in the direction indicated by the arrow and circulates around the respective agitating members 23, 22. The toner supplied to the position immediately after passing the right end portion is applied to the developing sleeve 21 after being subjected to the stirring action for the longest time. The present invention pays attention to this point and sets the recycled toner supply position R on the developer flow path S immediately after the application of the developer to the right end portion of the development sleeve 21 or on the downstream side in the vicinity thereof.

The recycled toner carried by the carrying screw 32 in the recycling pipe 31 connected to the cleaning device 10 is supplied from the recycled toner supply position R into the developing device 6 and flows through the developer passage S described above. According to the above, the developer is sufficiently mixed with the carrier for the longest time, stirred, and made into a triboelectrically charged homogeneous developer, which is applied to the peripheral surface of the developing sleeve 21.

As shown in the figure, a toner concentration sensor 29 is provided at an appropriate position on the right end portion of the auxiliary stirring member 23 (downstream of the recycled toner supply position R) on the developer flow path S. The toner concentration in the developing device 6 is detected, and new toner is supplied as needed, so that the toner concentration determined in the developing device 6 is always maintained.

On the other hand, the supply position of the new toner according to the present invention was set as follows. That is, as shown in FIG. 2, the auxiliary stirring member 23 is preferably provided at a suitable position on the developer flow path S between the recycled toner supply position R and the toner concentration sensor 29 described above.
A new toner supply position N is set in the vicinity of the right end portion of.

The new toner supplied into the developing device 6 from the new toner supply position N set as described above is supplied to each stirring member.
22 and 23 mix and agitate with the carrier for a long time which is almost equal to that of the above-mentioned recycled toner, so that a uniform developer which is triboelectrically charged is applied to the developing sleeve. In addition, even if recycled toner is supplied with an inconsistent amount of toner, the toner concentration sensor located downstream
Since the toner density in the developing device 6 is constantly detected by 29, the toner density in the developing device 6 is kept stable. In this way, the recycle toner supply position R, the new toner supply position N, and the toner concentration sensor 29 are set sequentially toward the downstream side on the developer flow path S immediately after the application of the developer to the developing sleeve 21 is completed. Therefore, the recycled toner and the new toner supplied to the developing device 6 are not only thoroughly mixed and stirred with the carrier, but also the toner amount is changed and the supply of the recycled toner is controlled in accordance with the supplied amount of the recycled toner. Therefore, the toner density in the developing device 6 after the toner density sensor 29 can be made extremely stable.

[0029]

According to the present invention, the toner supplied to the agitator of the developing device at the recycle toner supply position is supplied to the carrier over the longest distance of the developer flow path formed by the agitator over a long time. Due to sufficient mixing and stirring, a triboelectrically charged homogeneous developer was applied to the developing sleeve.

Further, the toner concentration in the developing device is always kept stable even if the toner concentration sensor provided in the proper position supplies the recycled toner whose amount of toner constantly changes. In addition, the new toner is agitated almost the same as the recycled toner.

[Brief description of drawings]

FIG. 1 is a top view showing a stirring state of a developer and a supply position of recycled toner according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a supply position of new toner according to an embodiment of the present invention.

FIG. 3 is a side sectional view showing a configuration of a developing device.

FIG. 4 is a side sectional view showing the configuration of the image forming apparatus.

[Explanation of symbols]

 3 Photoreceptor Drum 6 Developing Device 18 Image Forming Device 21 Developing Sleeve 22 Main Stirring Member 23 Auxiliary Stirring Member 24 Partition Plate 26 Housing 29 Toner Concentration Sensor N New Toner Supply Position R Recycled Toner Supply Position S Developer Channel

Claims (2)

[Claims] 1. In a developing device of an image forming apparatus equipped with a toner recycling device for collecting the toner remaining on the surface of the image carrier after transfer and supplying the toner to the developing device, the developing device stirs at least the developer. After the developer which has a plurality of stirring members, a partition plate, and a developing sleeve and is agitated through the periphery of each stirring member that is parallel to each other across the partition plate is applied to the developing sleeve. Immediately after or near the end of application of the developer to the developing sleeve on the developer flow path in which a loop-shaped developer flow path that circulates around each stirring member again is formed after shifting to the stirring of new developer A developing device for an image forming apparatus, which is provided with a recycled toner supply position on the downstream side. 2. A supply position of new toner according to claim 1, wherein a recycled toner supply position is provided on the developer flow path and a toner concentration detection means is provided downstream of the recycled toner supply position. A developing device for an image forming apparatus, which is provided between the developing devices.